The present invention relates generally to an improved hot air balloon structure, and more particularly to a hot air load-carrying balloon structure which is equipped with an improved cap valving means which may be controllably opened rapidly so as to assist in deflation, and thereby aid in descent and landing.
Hot air balloons have been utilized for an extended period of time, with this type of structure having contributed to the first known or recorded flight by man. While they are structurally different from gas balloons, they are responsible for an increased interest as a sporting activity because of the relatively low running costs, and a significant safety record.
In flight, a hot air balloon may assume what has been defined as a natural shape, that is a relatively wide and enlarged diameter at the top, tapering inwardly toward the bottom in accordance with a shape created by the internal pressure. Load tapes are provided to support loads being carried by the balloon, including the occupants of the basket, the burner, and the like. To provide heat for the air within the balloon envelope, a burner is provided which is normally fueled by propane gas or the like.
The base of the balloon is provided with a relatively large diameter opening in order to permit heat from the burner to enter the envelope. The lift for the structure is provided by periodically or intermittently firing the burner so as to increase the temperature of the air within the envelope. Ascent and descent is accordingly accomplished in this fashion. Because of the heat capacity of air, and the time required to achieve cooling and thus descent, the hot air balloons are normally provided with an opening at or near the pole cap, so as to permit the egress of hot air, to be replaced by cooler air.
In the past, a ripping panel had been typically employed at or near the top of the balloon, the ripping panel being opened upon landing so as to permit rapid deflation of the balloon. Typically, ripping panels are held in closed disposition with a self-fastening material such as Velcro or the like.
In order to provide a proper envelope material, woven tear-resistant materials such as nylon or the like is typically utilized, and treated with a film-forming substance such as polyurethane or the like in order to reduce porosity and increase the load carrying and flight characteristics. Such materials are, of course, commercially available.